Capability of Organically Modified Montmorillonite Nanoclay as a Carrier for Imidacloprid Delivery

Abstract

Organically modified clays have attracted increasing research attention for their various commercial and industrial applications, such as being carriers for pesticide delivery. Besides, the suitability and performance of commercially available organoclays could further promote their applicability. Hence, this study investigated the potential application of a commercially available alkylamine-modified montmorillonite (MMT) nanoclay as a carrier for a widely used insecticide, imidacloprid. X-ray diffraction and thermogravimetric analysis were employed to illustrate the arrangement, orientation, and conformation of surface-modifying agents (SMAs) on MMT nanoclay. It was observed that the clay was modified at an ∼1.0 cation exchange capacity, with the SMAs, especially octadecylamine, arranged in the MMT nanoclay as a bilayer to a pseudo-trilayer or a paraffin monolayer with a tilting angle of ∼25°, which indicated the nanoclay’s ability to adsorb a large amount of imidacloprid. The adsorption-desorption of imidacloprid to MMT nanoclay further confirmed this applicability. A high adsorption capacity (∼85 mg g-1) was observed, with a high reversibility in desorption, showing a hysteresis value of 0.75. Further, the adsorption kinetics and response of the nanoclay to imidacloprid revealed that, initially, a rapid sorption occurred due to a hydrophobic interaction. This was followed by a slower diffusion-controlled sorption due to hydrogen bonding to the internal binding sites. The releasing pattern of imidacloprid from the MMT nanoclay indicated its potential for the preparation of a slow-releasing pesticide formulation where the nanoclay will reduce the instantaneous release of the total amount of pesticide.